1. Field of the Invention
The present invention relates to a paper-feeding device and an image forming apparatus. More particularly, the present invention relates to a mechanism that aligns sheets stacked on the paper-feeding device.
2. Description of the Related Art
Image forming apparatuses including copiers, facsimiles, and printing machines heat and fix a transferred image on a sheet-like recording medium such as recording paper and an overhead projector (OHP) film (hereinafter, “recording sheet”) thereby obtaining a duplicated or printed output.
In a typical image forming apparatus, one of recording sheets stacked on a sheet cassette or a sheet tray provided with the image forming apparatus is sequentially conveyed to a transfer position.
In most cases, recording sheets with a frequently-used size are stacked on the sheet cassette or the sheet tray. For less frequently-used recording sheets or special sheets, Japanese Patent Application Laid-open No. 2006-219275 discloses an image forming apparatus that additionally includes a manual paper-feeding device.
The manual paper-feeding device is a cover capable of opening and closing. The cover is attached to a side wall of a housing of the image forming apparatus. Recording sheets can be staked on an upper surface of the manual paper-feeding device when it is open.
Japanese Patent Application Laid-open No. H11-59922 discloses a plate-like manual paper-feeding device provided with side fences on the upper surface for aligning side edges of the recording sheets. The side fences are a pair of guide fences each arranged parallel to each other and orthogonal to a feeding direction (hereinafter, “sheet-width direction”). The pair of side fences symmetrically moves with response to a center line therebetween by a mechanism using a pinion that meshes with racks. The pinion is arranged on the center line.
With remarkable downsizing of image forming apparatuses, image forming apparatuses can be installed on various locations.
An image forming apparatus is usually placed on the floor in an office. However, a downsized image forming apparatus can be placed not only on a desk but also at a position higher than a user's seated position. The position higher than the user's seated position corresponds to a highest level of a rack on which a computer can be mounted, a shelf that is placed on the desk, and the like.
When placed at a position higher than the user's seated position, the image forming apparatus is above the user's eye level.
For this kind of image forming apparatuses, recording sheets are used as copy output material. The recording sheets need to be refilled, or special sheets other than the recording sheets of a predetermined form are sometimes used. Accordingly, some image forming apparatuses are equipped with a feed cassette that can accommodate the recording sheets of the predetermined form, and, in addition to the feed cassette, a manual paper-feeding device on which sheets can be stacked, to feed special sheets.
An example of the manual paper-feeding device is explained below. Part of a side wall of the image forming apparatus includes a lid-like member that is capable of opening and closing. The lid-like member is tilted outward from the side wall of the apparatus to be opened and expose a face on which sheets are stacked, thereby forming a position in which the apparatus can feed special sheets and the like.
As another configuration for manual feeding other than the configuration that enables manual feeding by opening part of the side wall of the image forming apparatus, a sheet tray that is housed in the apparatus is pulled out to expose the stack face, thereby forming a position in which special sheets and the like can be fed.
The manual paper-feeding device having a configuration that is exposed outside the apparatus sometimes has side fences to align side edges of the sheets that are stacked on the stack face. Even when the image forming apparatus is placed at a position higher than the user's eye level, the side fences must be aligned with the side edges of the stacked sheets to prevent skew of the sheets.
To stack the sheets on the stack face when the stack face is higher than the user's eye level, the user tends to reach for the stack face and drop the sheets held in hand down on the stack face. In some cases, the user stands up each time to perform this task. Therefore, the operability is quite low.
Also, when the side fences are moved to be aligned with the side edges of the stacked recording sheets, the task as mentioned above is needed. To determine the positions of the side fences before the sheets are stacked, the user must stand up and look into the stack face from the above or the side. This procedure to prepare the recording sheets increases operation loads on the user who is seated.
The lid-like member that is installed in the manual paper-feeding device can be adapted to be moved up and down, to be lowered to the user's eye level. In such cases, a complicated mechanism like a lifting and lowering device is required, which leads to an increase in the cost of the apparatus.